The present invention relates to an improved arrangement for quenching the arcs formed in arresters and wherein for the purpose of current-limiting there are provided at least one device equipped with a discharge path and at least one resistor, and wherein means are included for bridging-over the resistor with a time delay after ignition of the discharge path has taken place.
An arrangement of this general type is already known from Swiss Pat. No. 512,845 and which has, for the purpose of avoiding any impairment of the protective characteristic of an arrester after the build-up of a discharge voltage, an arrangement comprising a discharge path followed by a resistor. This arrangement, however, comprises two separate structural components, namely, a discharge device for effecting current limitation, and a separate device including a firing chamber for effecting a bridging-over of the resistor. This is not an optimal solution, neither in an electrical nor in a mechanical respect because the use of two separate devices will obviously result in a substantial increase in cost of an arrangement for arc quenching and will furthermore require a corresponding large amount of space.
In my co-pending United States patent application Ser. No. 696,228 filed June 15, 1976 now U.S. Pat. No. 4,072,996 an arrangement for arc quenching in arresters is disclosed which comprises a discharge path in the form of a quenched arc gap located in a quenching chamber and a blow-out coil associated with the chamber for effecting a magnetic blow-out, i.e., lengthening of the arc, and wherein the quenching chamber is equipped, in addition to a pair of electrodes which establish the quenched arc gap, with an auxiliary electrode which together with the adjacent electrode of the quenched arc gap forms an auxiliary arc gap, and wherein the auxiliary electrode is also connected to that adjacent electrode by way of a blow-out coil. An arrangement of this type produces, by the use of relatively simple means, a high quenching capacity of the arrester due to the current which flows through the short-circuited blow-out coil at the instant of the follow-up current peak value independent of the follow-up current. The leakage current of such arresters protecting low-impedance current sources such as cable sections or batteries of condensers will rise very rapidly and can reach very high values. If this value exceeds a critical magnitude, it will effect the travel path of the arc and thus reduce the quenching capability of the arrester. For this reason, it will become necessary to connect a leakage resistance in series with the arc for the purpose of current limitation. The voltage drop across such resistance will be additive with the arc voltage. When the arc voltage has been built up after a certain period of time its magnitude will come close to the protection level of the arrester. Therefore, the sum of the arc and resistance voltages can easily exceed the protective level and result in destruction of the component which is desired to be protected by the arrester.
Published German patent application DT-OS No. 2,040,053 discloses an arc path arrangement for an arrester with magnetic blow-out and where, for the purpose of lengthening the arc and reducing the possibility of back-arcing, a plurality of quenching chambers are assembled in superposed relation and provided with openings for establishing the necessary electrical connections between adjacent chambers. Arrangements of this type will result in a lengthening of the arc by giving it a spiral-like configuration but not in limitation of the leakage current without a transgression of the protective level with a leakage resistance placed in succession.